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From: Wolfram Sang <wsa+renesas@sang-engineering.com>
To: linux-i2c@vger.kernel.org
Cc: linux-renesas-soc@vger.kernel.org,
	Luca Ceresoli <luca@lucaceresoli.net>,
	Kieran Bingham <kieran@ksquared.org.uk>,
	Jacopo Mondi <jacopo@jmondi.org>,
	Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
	Vladimir Zapolskiy <vz@mleia.com>,
	Wolfram Sang <wsa+renesas@sang-engineering.com>
Subject: [RFC PATCH 2/5] i2c: core: add new variant to check for a client
Date: Tue, 31 Dec 2019 17:13:57 +0100	[thread overview]
Message-ID: <20191231161400.1688-3-wsa+renesas@sang-engineering.com> (raw)
In-Reply-To: <20191231161400.1688-1-wsa+renesas@sang-engineering.com>

For the new 'alias' feature, we need to scan for devices while holding
the lock. We focus on read_byte transactions for now to keep things
simple. Requesting an alias will be rare, so there is not much overhead.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
---
 drivers/i2c/i2c-core-base.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index 20a726dc78db..51bd953ddfb2 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -2108,6 +2108,23 @@ static int i2c_default_probe(struct i2c_adapter *adap, unsigned short addr)
 	return err >= 0;
 }
 
+static int i2c_unlocked_read_byte_probe(struct i2c_adapter *adap, unsigned short addr)
+{
+	union i2c_smbus_data dummy;
+	int err;
+
+	if (i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_BYTE)) {
+		err = __i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
+				     I2C_SMBUS_BYTE, &dummy);
+	} else {
+		dev_warn(&adap->dev, "No suitable probing method supported for address 0x%02X\n",
+			 addr);
+		err = -EOPNOTSUPP;
+	}
+
+	return err >= 0;
+}
+
 static int i2c_scan_for_client(struct i2c_adapter *adap, unsigned short addr,
 			    int (*probe)(struct i2c_adapter *adap, unsigned short addr))
 {
-- 
2.20.1


  parent reply	other threads:[~2019-12-31 16:14 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-31 16:13 [RFC PATCH 0/5] i2c: implement mechanism to retrieve an alias device Wolfram Sang
2019-12-31 16:13 ` [RFC PATCH 1/5] i2c: core: refactor scanning for a client Wolfram Sang
2020-01-01 16:45   ` Laurent Pinchart
2020-01-07  9:26   ` Kieran Bingham
2020-01-07  9:53     ` Geert Uytterhoeven
2020-01-07  9:58       ` Kieran Bingham
2020-01-07 10:25       ` Wolfram Sang
2020-01-07 10:36         ` Geert Uytterhoeven
2020-01-07 11:23           ` Wolfram Sang
2020-01-07 15:03             ` Luca Ceresoli
2020-01-07 16:45               ` Wolfram Sang
2020-01-07 16:52                 ` Kieran Bingham
2019-12-31 16:13 ` Wolfram Sang [this message]
2020-01-01 16:49   ` [RFC PATCH 2/5] i2c: core: add new variant to check " Laurent Pinchart
2020-01-07  9:42   ` Kieran Bingham
2019-12-31 16:13 ` [RFC PATCH 3/5] i2c: core: add function to request an alias Wolfram Sang
2020-01-01 16:55   ` Laurent Pinchart
2020-01-02 18:58     ` Luca Ceresoli
2020-01-02 21:13       ` Wolfram Sang
2020-01-02 22:27         ` Luca Ceresoli
2020-01-03  0:10           ` Laurent Pinchart
2020-01-07 15:03             ` Luca Ceresoli
2020-01-07 17:13               ` Laurent Pinchart
2020-01-08 13:27                 ` Wolfram Sang
2020-01-08 13:31                   ` Laurent Pinchart
2020-01-08 13:38                     ` Wolfram Sang
2020-01-08 13:22               ` Wolfram Sang
2020-01-08 13:19             ` Wolfram Sang
2020-01-08 13:29               ` Geert Uytterhoeven
2020-01-08 13:34               ` Laurent Pinchart
2020-01-02 21:03     ` Wolfram Sang
2020-01-21  9:05     ` Peter Rosin
2020-01-07  9:40   ` Kieran Bingham
2020-01-07 17:11     ` Laurent Pinchart
2020-01-07 17:14       ` Kieran Bingham
2020-01-08 13:35         ` Wolfram Sang
2020-01-08 13:36           ` Laurent Pinchart
2019-12-31 16:13 ` [RFC PATCH 4/5] i2c: core: add simple caching to the 'alias' scanning Wolfram Sang
2020-01-07  9:59   ` Kieran Bingham
2020-01-21  9:22   ` Peter Rosin
2019-12-31 16:14 ` [RFC PATCH 5/5] simple test case for the I2C alias functionality Wolfram Sang
2019-12-31 16:27 ` [RFC PATCH 0/5] i2c: implement mechanism to retrieve an alias device Wolfram Sang

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